Eddystone EID and eTLM support

[hadrienk]

I am making the PR before I am done to get some review. I am trying to implement the EID and eTLM logic (as mentionned in #21).

• So far, I am only focusing on the encryption decryption logic. I am setting the key manually.
• I do not have any beacon that sends eTML frames yet so the tests are solely based on my understanding of the spec.

If anyone has experience with eddystone in production or hardware we could test my code against please let me know.

[hadrienk]

@manufacturedba maybe you have means to test?

[manufacturedba]

Yep - I should be able to still. I'll follow up this week.

[hadrienk]

@manufacturedba good, let me know if I can be of any help.

[manufacturedba]

Turns out my proximity estimote beacon doesn't support EID. It's only the location beacons :(

[hadrienk]

Åh that's too bad. Thanks you for looking into it though. I'll try to get a colleague to write a firmware for some of our hardware.

[rzr]

Any traction for this change ?

Eventually try to rebase on:
https://github.com/abandonware/node-eddystone-beacon-scanner